Integrated circuit with asymmetric mirrored layout analog cells

ABSTRACT

In a first integrated circuit column, a first cell active area top edge is separated by a first separation distance from a first barrier line, a first cell active area bottom edge is separated by a second separation distance from a second barrier line, a second cell active area top edge is separated by the second separation distance from a third barrier line, and a second active area bottom edge is separated by the first separation distance from a fourth barrier line. In a second column a third cell active area top edge is separated from a fifth barrier line by the first distance, and a third cell active area bottom edge is separated from a sixth barrier line by a third distance. The first and third separation distances are different from the second separation distance. The first barrier line aligns with the fifth barrier line.

BACKGROUND

Integrated circuits contain one or more semiconductor devices.Integrated circuits are represented by plan view diagrams called layoutdiagrams, which contain information about the size, position, andorientation of elements of the semiconductor devices located therein.Integrated circuits are manufactured using cells, or groups offunctional elements, that perform low level functions of thesemiconductor device. Cells are standard or custom cells, according to adesired design of a semiconductor device and a desired manufacturingplan that balances semiconductor device size on a substrate, with costassociated with designing and manufacturing the integrated circuit.

Cells are organized into libraries according to size, function, or otheraspects of the cell. Standard cells in a library are analog or digital.Standard cells have at least one dimension in common with other cells ofthe library, such as a standard length of the cells. Standard cells of alibrary facilitate layout of a semiconductor device and reduce thecomplexity of designing an integrated circuit by using pre-characterizedstandard cells, with known performance characteristics, and regular cellpositions on the substrate of the integrated circuit. Layout ofsemiconductor devices with custom cells or non-standard cells withstandard cells is also more complex than layout of semiconductor deviceswith only standard cells. Reduced complexity of semiconductor devicedesign is a desirable outcome.

Custom cells, or non-standard cells, with dimensions that differ fromthe standard cell dimension, have an increased risk of defects ordeviations from desired electrical performance parameters in theintegrated circuit because of manufacturing errors. Structural defectsand/or deviating performance parameters of an integrated circuitincrease a manufacturing cost for said integrated circuits, and resultin premature device failure, elevated power consumption, or irregulardevice performance. Decreased manufacturing defect levels is a desirableoutcome of integrated circuit manufacturing processes.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a block diagram of a semiconductor device in accordance withsome embodiments of the present disclosure.

FIG. 2 is a plan view of adjacent symmetric cells of an integratedcircuit, according to some embodiments.

FIGS. 3A-3B are plan views of cells in an integrated circuit, accordingto some embodiments.

FIG. 4 is a plan view of a block of cells in an integrated circuit,according to some embodiments.

FIG. 5 is a plan view of a block of symmetric and vertically asymmetriccells in an integrated circuit, according to some embodiments.

FIG. 6 is a plan view of a block of asymmetric cells in an integratedcircuit, according to some embodiments.

FIG. 7 is a cross-sectional diagram of a semiconductor device in anintegrated circuit, according to some embodiments.

FIG. 8 is a flow diagram of a method of making integrated circuits,according to some embodiments.

FIG. 9 is a schematic view of a system for designing an integratedcircuit layout design according to some embodiments.

FIG. 10 is a block diagram of a manufacturing system for makingintegrated circuits, according to some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components, values, operations, materials,arrangements, or the like, are described below to simplify the presentdisclosure. These are, of course, merely examples and are not intendedto be limiting. Other components, values, operations, materials,arrangements, and the like, are contemplated. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” or the like, may be used herein for ease of descriptionto describe one element or feature's relationship to another element(s)or feature(s) as illustrated in the figures. The spatially relativeterms are intended to encompass different orientations of the device inuse or operation in addition to the orientation depicted in the figures.The apparatus may be otherwise oriented (rotated 90 degrees or at otherorientations) and the spatially relative descriptors used herein maylikewise be interpreted accordingly.

An integrated circuit having individual cells arranged by columnsincludes cells that are vertically symmetric, and cells that arevertically asymmetric. Vertically symmetric cells have a same amount ofseparation between fins in the cell active area and cut poly lines(e.g., oxide insulating structures between active areas in an integratedcircuit). Vertically asymmetric cells have a different amount ofseparation between fins of the cell active area and the top and bottomcut poly lines. Cells with vertical asymmetry have cut poly lines thatalign with cut poly lines in cells of other columns of the IC. Cellswith vertical asymmetry have active area borders and/or edges thatalign, along the direction of the fins, with active area borders and/oredges of cells in other columns of the IC. Vertical asymmetry of somecells occurs in pairs of adjoining cells in a column of an IC: two cellshaving vertical asymmetry have mirrored layouts and spacings between thecell active areas and the cell cut poly lines.

FIG. 1 is a block diagram of a semiconductor device 100, in accordancewith at least one embodiment of the present disclosure. In FIG. 1,semiconductor device 100 includes, among other things, a circuit macro(hereinafter, macro) 102. In some embodiments, macro 102 is a transistormacro. In some embodiments, macro 102 is a macro other than a transistormacro. Macro 102 includes, among other things, one or morestandard-cell-adapted FinFET arrangements 104A. In some embodiments,macro 102 includes, among other things, one or more arrangements 104Aand one or more arrangements 104B. In some embodiments where one or morearrangements 104A and one or more arrangements 104B are included,arrangement 104A differs from arrangement 104B. Examples of each ofarrangement 104A and 104B include arrangements in semiconductor devicesfabricated based on corresponding layout diagrams shown in each of FIGS.3-6, or the like.

Integrated circuits include groups of circuit components that areconfigured to perform predetermined circuit functions. Examples of suchintegrated circuit (IC) functions include receiving signals, sendingsignals, communication between components of an IC and on other ICs,storing data, performing calculations, and managing IC functionality(memory controllers, IC timing circuit elements, and other similarfunctionality). Groups of circuit components may be pre-configured asstandard cells that are arranged in an integrated circuit layout processprior to an integrated circuit manufacturing process. Standard cellsfacilitate simplified circuit performance simulation using thepredetermined blocks, or standard cells, of the circuit design. Someembodiments of standard cell libraries include purely digital circuitcomponents. Some embodiments of standard cell libraries include purelyanalog circuit components. Some standard cell libraries include mixturesof digital and analog circuit components configured to work together ina single integrated circuit.

Integrated circuit manufacturing involves using standard cells in celllibraries to simplify a design process for integrated circuits. In someembodiments, simplified design processes using standard cells inlibraries limits a manufacturer's ability to maximize circuit componentdensity of an integrated circuit. Standard cells have a standard celllength in a first direction and a standard cell width in a seconddirection (different from the first direction) so that cell borders ofthe standard cell align with the cell borders of other standard cells(the cell borders forming a regular grid, and the cell active areasbeing evenly distributed within the regular grid of standard cellborders), and so that cell components within standard cells have astandard separation or spacing from a cell border. In some embodiments,the second direction is perpendicular to the first direction. A standardcell size is desirable in integrated circuit design and manufacturing inorder to simplify the abutment of adjacent cells in rows and columns ofthe integrated circuit. Standard size cells contain, within the area ofthe standard cell, a certain number of active fins or active lines thatare used to form circuit elements. However, some circuit elements of anintegrated circuit do not use the same number of fins as are present inthe standard size cell (a “normal” number of fins) in order to function.Some circuit elements use a smaller number of fins (a “low” number offins), and some circuit elements use a larger number of fins (a “high”number of fins). Such different size cells have different cell lengthsin a first direction extending across, or perpendicular to, thedirection in which the fins extend on a substrate. Abutting cells havingdifferent cell lengths present some difficulty with alignment (in asecond direction, along the direction of the fins) of cell elements inother columns. In some embodiments, the cells for which alignment isdesired are in adjoining columns. In some embodiments, the cells forwhich alignment is desired are in columns separated by another column.Integrated circuits with cells having different cell lengths sometimesalign same types of cells into columns along the first direction(perpendicular to the fins) or rows (parallel with the fins). Cellelement misalignment issues arise when the lengths of cells in onecolumn are different from the lengths of cells in a different column,when cells have symmetric layouts along the first direction, asdescribed below.

Cells in cell libraries have preconfigured layouts with predictable andconsistent performance and known levels of interference with other partsof an integrated circuit. Integrated circuit design aims to reduceinterference as much as possible, and to maintain performance of circuitelements within desired parameters. To preserve performancecharacteristics of the cells within anticipated ranges in completedcircuits, a baseline separation distance exists between components of acell and circuit elements of adjoining cells of the circuit. Thebaseline separation distance is an interior separation distance betweena cell border and elements of the circuit within a circuit cell.

Vertically symmetric cells have a same distance between the cell activearea and the top and bottom edges of the cell. In some embodiments, avertically symmetric cell has one separation distance between the cellactive area and a cell border shared with a cell within the column(e.g., the top and bottom edges of the cell), and a different separationdistance between the cell active area and cell borders of adjacentcolumns. In some embodiments, a vertically symmetric cell has a singleseparation distance between the cell active area and all cell borders.

Vertical symmetry of a cell is independent of cell length. In someembodiments, vertically symmetric cells having a same cell length havedifferent separation distances between cell active areas and top andborders of the cells. Vertically symmetric cells having different celllengths generally have different active area lengths, and differentvertical separation distances between active areas and top and bottomedges of cells in a column of cells. Manufacturers use standard celllengths whenever possible to reduce, as much as possible, interferenceor coupling of cell elements in active areas of cells, and to simplifylayout of cells in an integrated circuit.

When cells are formed in an integrated circuit, a plurality of lines areetched into a semiconductor substrate in preparation for cell formation.In some embodiments, the semiconductor substrate is a silicon substrate,although other substrates are included within the scope of the presentdisclosure. The substrate may be one of an elementary semiconductormaterial, a compound semiconductor material, and/or an alloysemiconductor material. Examples of elementary semiconductor materialsinclude, but are not limited to, monocrystalline silicon (Si),polycrystalline silicon (poly-Si), amorphous silicon (a-Si), germanium(Ge), and/or diamond (C). Examples of binary compound semiconductormaterials include, but are not limited to, IV-IV materials includingsilicon germanium (SiGe), germanium carbide (GeC), and silicon carbide(SiC), and III-V materials including gallium arsenide (GaAs), galliumphosphide (GaP), indium phosphide (InP), indium arsenide (InAs), and/orindium antimonide (InSb). Examples of tertiary and quaternary compoundsemiconductor materials include, but are not limited to, GaAsP, AlInAs,AlGaAs, GaInAs, GaInP, and/or GaInAsP. Within the present disclosure,lines of a semiconducting substrate shall be referred to as poly linesfor simplicity and clarity, although other materials than polysiliconare contemplated.

During a manufacturing process, cell borders are formed by etching somelines away, leaving rows of active lines in active areas of the cellsbetween the etched regions. Adjacent active areas of an integratedcircuit are separated from each other by isolation structures thatreduce cross-talk or inadvertent signal transfer between active areas.Some isolation structures include dielectric structures formed bydepositing dielectric material into the spaces formed after removal ofdummy or inactive lines. Dielectric material thus deposited electricallyisolates poly lines in different cells from each other, and electricallyisolates poly lines within a same cell from each other. Some isolationstructures include cut poly lines, or breaks in the continuous linesthat extend across a substrate. Some cut poly lines are used to etch thepoly lines to form spaces or breaks that extend in a directionperpendicular to the run direction of the lines of the active areas.Some cut poly lines are used to etch one or more long segments of anundoped poly line located at a border between adjoining active areas ofan integrated circuit.

Some isolation structures include barrier lines, or poly lines that arebetween active areas of an integrated circuit. A barrier line is anundoped poly line, similar to the doped poly lines of a gate structurethat physically separates doped poly lines in one active area from dopedpoly lines of the adjoining active area. A barrier line extends inparallel to doped poly lines of an integrated circuit that form part ofactive areas of the integrated circuit. A barrier line has a center thatextends down the middle of the barrier line, parallel to the edge of thebarrier line, and parallel to the centers of doped poly lines in theactive areas of the integrated circuit that adjoin the barrier line. Theseparation distance between an active area and a barrier line at a cellborder of the active area is determined using Equation 1, below, bymultiplying the fin pitch by an integer representing a number of fins,and adding a width corresponding to half the width of a single fin:

$\begin{matrix}{{SD} = {{n \times p} - \frac{w}{2}}} & {{Equation}\mspace{14mu} (1)}\end{matrix}$

where SD=separation distance, p=fin pitch, w=fin width, and n=1, 2, 3 .. . (a number of fins originally present between the edge of the activearea and the cell edge).

As discussed herein, the term “second direction” refers to a directionaligning with a longitudinal axis of barrier lines and fins of an activearea, and the term “first direction,” corresponds to a directionperpendicular to the second direction, across the barrier lines or finsof active lines of the integrated circuit. Cells are arranged in columnsthat extend along the first direction and adjoin each other in thesecond direction. Column borders also extend along the first direction.A barrier line extends in the second direction. A cut poly line is alike demarking the break in a silicon material of a barrier line (anundoped poly line) or a doped poly line of an active area of theintegrated circuit. Barrier lines correspond to cell borders that extendin the second direction. Thus, the terms “top” and “bottom” refer topositions along the first direction, and the terms “left” and “right”refer to positions along the second direction, with respect to a centerof an active area of the integrated circuit. The term “vertical” refersto orientations with respect to the first direction, and the terms“lateral” or “horizontal” refer to orientations with respect to thesecond direction. Cell length and active area length are measured alongthe first direction, and cell width is measured along the seconddirection. An active area of a cell is vertically situated between thetop and bottom barrier lines of a cell. Adjacent cells, whether in thefirst direction or in the second direction, share a cell border. Abarrier line between two adjacent active areas has a centerline thatcorresponds to the shared cell border of the two adjacent active areas.A cut poly line has a centerline corresponding to the center of the gapbetween the truncated poly lines of active areas that adjoin each otheralong the second direction. A centerline of a cut poly line correspondsto a shared cell border of the two adjacent active areas.

The present disclosure relates to asymmetric cells in an array of cells,where a first asymmetric cell is arranged vertically with anotherasymmetric cell having a layout that mirrors, across a shared cellboundary, the layout of the first asymmetric cell. Mirrored, or flipped,cells form mirrored pairs of cells. Separation distances in mirroredpairs of vertically asymmetric cells arranged in columns are adjusted toalign edges of active areas in the mirrored pair of cells, with edges ofactive areas in laterally adjacent columns, to improve alignment of cellelements. By improving alignment of cell active areas in laterallyadjacent columns, manufacture of integrated circuits is simplified,yield of integrated circuits increases, and/or performancespecifications of integrated circuits are closer to desiredspecifications. A clarifying presentation of how strict adherence tocell symmetry in laterally adjoining cells of an integrated circuit,where the laterally adjoining cells have different cell lengths, isgiven below, to show how lateral misalignment of cell element occurs.

FIG. 2 is a plan view of an integrated circuit 200 having symmetricstandard cells with cell lengths measured in a first direction 101 andcell widths measured in a second direction 103. Integrated circuit 200includes standard cell 206 in column A, having a first cell length 206Mand a standard cell perimeter 206 p. A top edge 206 t of standard cell206 corresponds to a centerline 208L of a first cut poly line 208. Abottom edge 206 b of standard cell 206 corresponds to a centerline 210Lof a second cut poly line 210. Standard cell 206 includes active area212 having a top edge 212 t and a bottom edge 212 b parallel to eachother and to top edge 206 t and bottom edge 206 b of standard cell 206.Top edge 206 t and top edge 212 t are separated by a first separationdistance 214 (also known as a uniform separation distance or a commonseparation distance). Bottom edge 206 b and bottom edge 212 b are alsoseparated by separation distance 214. Because separation distance 214 isbetween both the top edges 206 t and 212 t, and bottom edges 206 b and212 b, standard cell 206 is vertically symmetric. Standard cell 206 hasfirst cell length 206M measured from top edge 206 t to bottom edge 206b. A centerline 206L is equidistant between top edge 212 t and bottomedge 212 b (see distance 212 d), and between top edge 206 t and bottomedge 206 b (distance 212 d+separation distance 214).

Integrated circuit 200 includes standard cells 220 and 230 in column Bthat adjoins column A. In column B, cut poly line 222 at a top ofstandard cell 220 corresponds to a same line as cut poly line 208 ofcolumn A, and cut poly line 232 at a bottom of standard cell 230corresponds to a same cut poly line as cut poly line 210 in column A. Incolumn B, standard cell 220 and standard cell 230 share cut poly line226. A centerline 226L of cut poly line 226 extends through a center ofstandard cell 206 (e.g., centerline 206L), and a center of active area212 within standard cell 206 (e.g., centerline 212L).

In standard cell 220, top edge 220 t corresponds with centerline 222L ofcut poly line 222, and the bottom edge 220 b corresponds with centerline226L of cut poly line 226. Centerline 226L also corresponds with the topedge 230 t of standard cell 230 and with centerline 206L of symmetriccell 206. Standard cell 220 includes, between cut poly lines 222 and226, an active area 224, with an active area top edge 224 t and anactive area bottom edge 224 b, where active area top edge 224 t isbetween active area bottom edge 224 b and cut poly line 226. Standardcell 220 has a cell perimeter 220 p, and a cell length 220M that is halfthe length of cell length 206L.

Standard cell 230 has a cell perimeter 230 p, and a cell length 230Mthat is half the length of cell length 206L. The top edge 230 t ofstandard cell 230 corresponds with the centerline 226L of cut poly line226, and with the centerline 206L of standard cell 206. The bottom edge230 b of standard cell 230 corresponds with a centerline 232L of cutpoly line 232. Standard cell 230 contains a second active area 234 witha top edge 234 t and a bottom edge 234 b, where top edge 234 t isbetween bottom edge 234 b and cut poly line 226.

Standard cells 220 and 230 have the same layout: active area 224 iscentrally located within standard cell 220 between cut poly lines 222and 226, and where active area 234 is centrally located within standardcell 230 between cut poly lines 226 and 232. Thus, a separation distancein the first direction between an edge of either of symmetric cells 220or 230 and the centerline of the nearest cut poly line at the top of thecolumn, the bottom of the column, or at the center of the column, is thesame distance. Thus, each of: the centerline 222L and top edge 224 t,the centerline 226L and bottom edge 224 b, the centerline 226L and topedge 234 t, and centerline 232L and bottom edge 234 b, are separated byseparation distance 240. Because both of symmetric cells 220 and 230 aresymmetric, the cells mirror each other across the centerline 226L.

Standard cells 220 and 230 are individually vertically symmetric. Theactive area of each cell is located at the center of the cell, and auniform separation distance between the active area and at least the topand bottom edges of the cell is preserved. However, because of adherenceto this common design rule, the edges of active area 212 in standardcell 206 are misaligned with edges 224 t and 226 b of standard cells 220and 230. Top edge 212 t of standard cell 206 is farther from sharedcenterline 208L/222L than top edge 224 t (e.g., first separationdistance 214 is larger than separation distance 240). Bottom edge 212 bis farther from shared centerline 220L/232L than bottom edge 234 b(first separation distance 214 is larger than separation distance 240).The difference between first separation distance 214 and separationdistance 240 is the offset distance 242 between standard cell 206 andcells 220 and 230.

Active area offsets or edge misalignments in IC designs, as shown inFIG. 2, lead to device performance issues or manufacturing problemsbecause of difficulties with pattern transfer from a patterning templateto the integrated circuit. Patterning templates include photolithographymasks or reticles for transferring pattern information to layers coatedon a substrate of an integrated circuit. Active area offsets or edgemisalignments are, in some embodiments of integrated circuits or methodsof making integrated circuits, smaller than a wavelength of light.Methods of making pattern transfer templates, including photolithographymasks, are prone to preserving alignment of adjoining features on thetransfer template, at the expense of preserving specified dimensions ofthe adjoining features according to the planned integrated circuitlayout. Misalignment of cell elements in the second direction results inan increased risk of defects during a manufacturing process. Masking andpattern transfer issues result in poly lines or other cell features thatare too narrow or too wide in the first direction. In some instances,such misalignment/dimensional deviation results in line tipping,enhanced breakage, excessive switching times, long gate lengths, and soforth.

In some embodiments, such as shown in FIG. 3A, integrated circuitsinclude standard cells of different sizes. Arrays of standard cellsinclude standard analog cells, also called “full size” or “standard”cells, which have a standard length in a first direction and a standardwidth in a second direction. The first direction and the seconddirection should be interpreted herein as shown in FIG. 3A. Somestandard cell libraries, and integrated circuits based thereon, includecells with cell lengths that are integer multiples of the standard celllength. Some standard cell libraries, and integrated circuits basedthereon, include cells with cell lengths that are non-integer multiplesof the standard length L of the cell library. A cell length is measuredin the first direction 101. In some embodiments, a standard cell of thecell library has standard length L, and other cells in the library havea cell length L2, where L2=0.5L, and/or, a length L3, where L3=1.5L.Although non-integer multiples of the standard cell length (e.g.,L2=0.5L, and L3=1.5L), other non-integer multiples of the standard celllength are also envisioned for cells in the standard library fallingwithin the scope of the present disclosure. In some embodiments ofstandard cells, and integrated circuits based thereon, some cells havecell lengths that are integer multiples of the standard length. Layoutof such “integer-multiple” standard cells is simpler than layout of“non-integer multiple” cell length cells, because “integer-multiple”cells preserve, among them, a same separation distance as found instandard cells of the library because the top and bottom edges of cellsalign smoothly with the traditional gridded layout of standard cells inan integrated circuit. A ratio of the length of a standard cell and anon-standard cell does not need to correspond to the ratio of thelengths of the active areas in standard and non-standard cells thatadjoin each other in the second direction. Other non-integer multiplecell length standard cells (e.g., 2.5, 3.5, and so forth) are alsoenvisioned within the scope of the present disclosure.

FIG. 3A is a plan view of an array of analog cells in an integratedcircuit 300, according to some embodiments. In FIG. 3A, a plurality ofstandard cells are arranged according to some embodiments of the presentdisclosure. Some standard cells in integrated circuit 300 are symmetric,and some are singly asymmetric, but arranged in pairs to have mirroringsymmetry or flipped symmetry with each other and have lateral alignmentof cell elements with cells in different columns. Cells of integratedcircuit 300 have a cell width 301 in the second direction. In someembodiments, cells of the integrated circuit all have the same cellwidth. In some embodiments, cells of the integrated circuit havedifferent widths in different columns. In some embodiments, some columnsof cells share a common cell width with cells of another column, and thetwo columns adjoin each other. In some embodiments, some columns ofcells share a common cell width with cells of another column, and thetwo columns are separated from each other by a column with cells havinga different cell width. Cells of integrated circuit 300 are arrangedinto four columns, as follows. A first column 302A, has two cells:analog cell 304 with active area 304A, and analog cell 306 with activearea 306A. Cells 304 and 306 in first column 302A are bounded by topmostcut poly line (or barrier line) 308 at a top of the column in the firstdirection 101, a second barrier line (or center barrier line) 310, and abottom-most barrier line 312. The cells shown in the first column 302Aare vertically asymmetric cells (individually), but the pair exhibitsmirroring symmetry (or, flipped symmetry) centered on central barrierline 310.

Mirroring symmetry of pairs of cells in a column of standard cellsresults in each of the top and bottom cells in a mirrored pair of cellshas a same cell length, a same size active area, and a shared barrierline (the central barrier line of the mirrored pair of cells) aboutwhich the symmetry focuses. In a mirrored pair of cells, the separationdistance between the mirrored cell boundary (the centerline of theshared central barrier line) and the closest edge of an active area of acell in the mirrored pair (also called the inner separation distance) isthe same as in each cell. Similarly, the separation distance between theedge of a cell's active area and the boundary opposite the mirrored cellboundary (also known as the outer separation distance) is the same ineach other cell, and is different from the inner separation distance.

Cells in integrated circuit 300 are divided into cell blocks. In column302A, cell 304 and cell 306 are symmetric around center barrier line 310and comprise a first cell block B1. As described hereafter, other cellsin the array are divided into cell blocks, such as blocks B2, B3, andB4. A block includes a single cell, a pair of cells that are verticallysymmetric (such as cells 304 and 306), or multiple pairs of cells thatare vertically symmetric (such as cells 328, 330, 332, 334, 336, and338). Block B4 has a block length equal to the standard length of acell. Blocks B2 and B3 have a block length equal to 1.5 times thestandard length of a cell. Block B1 has a block length equal to 3 timesthe length of the standard length. Cell blocks typically have a blocklength that is an integer multiple (1×, 2×, 3×, and so forth) of thestandard cell length of the array of analog cells, or a non-integermultiple (0.5×, 1.5×, and so forth) of the standard cell length. A blocklength of a mirrored pair of cells correlates with the symmetry patternof separation distances in the mirrored pair of cells, and cells in adifferent column, as is described below.

In a symmetric cell, the terms “top” and “bottom,” when referring toelements of the cell, refer to the elements on opposite sides of thecenterline of the cell, where the elements are separated along the firstdirection. In pairs of cells, the terms “top” and “bottom” retain thesame orientation as for symmetric cells with regard to the first andsecond directions as described in FIG. 3A. The terms “topmost” and“bottommost” refer to elements of the pair of cells that are at agreatest distance from each other in the first direction. For example,in column 302A, the pair of cells includes cells 304 and 306, andbarrier line 308 is a topmost barrier line, barrier line 312 is abottommost barrier line, and barrier line 310 is the center barrier lineof the mirrored pair of cells. In discussions of groups of cells thatspan multiple columns, the terms “topmost” and “bottommost” generallyretain the meaning reserved for pairs or groups of cells that are in asingle column, i.e., cell elements at a greatest distance from eachother. “Topmost” and “bottommost” may also be used in reference to cellelements within a repeating block, or mirrored pair of cells, whenmultiple mirrored pairs in a first column vertically adjoin each otherwithin the length of a single cell, or a single mirrored pair of cellswith a different cell length, in a second column. (See, e.g. cells incolumn 302A and 302B, where standard cells 328 and 338 are topmost andbottommost cells in the column, and cut poly lines 314 and 336 aretopmost and bottommost barrier line segments shared with cells 304 and306 in column 302A, but, within the topmost mirrored pair of cells incolumn 302 b, comprising cells 328 and 330, the topmost and bottommostbarrier lines are cut poly lines 314 and 318.

Integrated circuit 300 includes a second column 302B, which includesthree mirrored pairs of vertically asymmetric cells: a first mirroredpair of cells includes cells 328 and 330, a second mirrored pair ofcells includes cells 332 and 334, and a third mirrored pair of cellsincludes cells 336 and 338. The first mirrored pair of cells includestop barrier line 214, central barrier line 316, and a bottom barrierline 318. Second mirror pair of cells includes top barrier line 318,central barrier line 320, and bottom barrier line 322. Third mirroredpair of cells includes top barrier line 322, central barrier line 324,and bottom barrier line 326. Whether a barrier line is labeled as “top”or “central” or “bottom” depends on the position of the active areas ofthe pair of cells in a mirrored pair of cells. Thus, while a line is atop barrier line in one mirrored pair of cells, the same line is abottom barrier line in a mirrored pair of cells that is above the firstmirrored pair of cells, or further along the first direction from thefirst mirrored pair of cells. For example, barrier line 318 is thebottom barrier line for cell 230, and the top barrier line for cell 332,the bottommost barrier line for first mirrored pair of cells 328/330,and the topmost barrier line for mirrored pair of cells 332/334. Suchconvention for referring to barrier lines is followed throughout thepresent disclosure. For first mirrored pair of cells 328/330, thecentral barrier line 316 adjoins inner separation distances that aresmaller than outer separation distances between the active areas of thecells and outer barrier lines 314/318. Similarly, for second mirroredpair of cells 332/334, inner separation distances proximal to centralbarrier line 320 are smaller than outer separation distances between theactive areas of the cells and outer barrier lines 318/322, and, forthird mirrored pair of cells 336/340, inner separation distancesproximal to central barrier line 324 are smaller than outer separationdistances between the active areas of the cells and outer barrier lines322/326.

Integrated circuit 300 contains a third column 302C having threesymmetric standard cells 344, 346, and 350. Cell 344 has top barrierline 340 and bottom barrier line 342, cell 346 has top barrier line 342and bottom barrier line 348, and cell 350 has top barrier line 348 andbottom barrier line 352. Bottom barrier line 352 is a same cut poly lineas barrier line 326 and barrier line 312 of columns 302B and 302A. Topbarrier line 340 is the same cut poly line as barrier line 314 of column302B and barrier lines 308 of column 302A. The separation distance inthe first direction between each active area of cells 344, 346, and 350and each cut poly line at a top edge or a bottom edge of the cells isthe same separation distance, or the uniform separation distance (of asymmetric standard cell).

Cell 344 is the simplest block of integrated circuit 300 shown herein, asingle cell having the standard cell length, equal to block length B4,in the first direction, wherein the active area is symmetricallypositioned between top and bottom barrier lines/edges of the cell in thefirst direction. Vertically asymmetric cells 328 and 330 in column 302Bare a mirrored pair of cells, comprising a second block of cells havingthe block length B4. Each of asymmetric cells 328 and 330 (also calledthe first mirrored pair of cells, as described above) has a cell lengththat is half of the standard length, and half of the block length B4.According to some embodiments, cell blocks comprise mirrored pairs ofcells having a shared central barrier line or mirrored cell boundary,such as barrier line 316 between asymmetric cells 328 and 330.Accordingly, the second mirrored pair of cells 332/334 is a block ofcells with a central barrier line 320 and block length B4, and the thirdmirrored pair of cells 336/338 is another block of cells with centralbarrier line 324 and block length B4. For each block of cells, or foreach mirrored pair of cells, in column 302 b, the inner separationdistance is different form the outer separation distance of the block ormirrored pair of cells.

Integrated circuit 300 contains a fourth column 302D having twovertically asymmetric cells 356 and 360, similar to the verticallyasymmetric cells of the block of cells/mirrored pair of cells in column302A, i.e., cell 304 and cell 306. Cell 356 has an active areapositioned between top barrier line 354 and central barrier line 358,and cell 360 has an active area situated between top barrier line 358and 362. Like mirrored pair of cells 304/306, the inner separationdistance between central barrier line 358 and the active areas isdifferent from the outer separation distance between the active areasand outer barrier lines 354 and 362.

FIG. 3A is a plan view of a non-limiting embodiment of an integratedcircuit having standard cells and cells with non-standard (shortened orelongated) cell lengths. In some instances, when making cells withnon-standard cell lengths, barrier lines are trimmed during etchprocesses. Trimmed lines contribute to parasitic capacitance, powerconsumption, slower toggle times for a circuit element containing thecell, and/or device damage because trimmed lines are susceptible totipping and breakage in manufacturing. Trimmed lines also interfere withthe doping of non-trimmed lines in a cell, leading to a non-uniformdistribution of switching times and/or leakage current through a cell.FIG. 3B is a plan view of a non-limiting representation of someembodiments of cells similar to those of FIG. 3A. FIG. 3B is a plan viewof an array of cells 370 that includes three cells: cell 370A, having astandard cell length 380, and cells 370B and 370C, having a shortenedcell length 381. Shortened cell length is half of the standard celllength 380. Cell lengths are measured in a first direction 101. Cell370A has a top barrier line 371 that is a shared top barrier line withcell 370B. Cell 370A has a bottom barrier line 371 that is a sharedbottom barrier line with cell 370C. Cells 370B and 370C are separated bya central barrier line 373. Cell 370A is separated from cells 370B and370C by barrier line 374. Barrier line 374 separates columns of cells inthe array of cells 370.

Lines 375A-375K extend along second direction 103. Lines are formed byetching a plurality of fins into a substrate, such as a semiconductorsubstrate, as described herein. Active areas are formed from a pluralityof fins by forming isolation structures between the active areas. Insome embodiments, a dielectric barrier is formed by etching an openingto a depth in the substrate that is greater than the depth of the finsin the substrate, and filling the opening with dielectric material, aswith some trench isolation techniques. Cell 370A has an active area 376between barrier lines 371 and 372 that includes segments of lines375A-375K. Each line segment of active area 376 is an original finwidth, with no trimming. The active area 376 is symmetrically positionedbetween barrier lines 371 and 372.

Cell 370B has an active area 377 that includes segments of lines 375Athrough 375E. Active area 377 is symmetrically positioned betweenbarrier lines 371 and 373. The segments of lines 375A-375D in activearea 377 are original-width fins, while line segment 375E-2 is a trimmedline segment. Line segment 375E-1 in active area 376 is anoriginal-width fin. Cell 370C includes active area 378 with segments oflines 375G-375L. Active area 378 is symmetrically positioned betweenbarrier lines 373 and 372. The segments of lines 375H-375K areoriginal-width fins, while line segment 375G-2 is a trimmed linesegment. As with line segment 375E-1, line segment 375G-1 in active area376 is an original-width fin. Active areas 377 and 378 are convertedinto vertically asymmetric active areas in cells 370B and 370C bymodifying a width, in the first direction, of barrier line 373 toeliminate the trimmed line segments 375E-2 and 375G-2. Thus, theoriginal-width fins at the top and bottom edges of active areas 377 and387 have, in cells where trimmed line segments are eliminated, moreuniform doping characteristics and electrical properties than in cellswhere trimmed line segments remain.

FIGS. 4-6 are plan views of details of integrated circuit 300 tohighlight aspects of the present disclosure. Integrated circuit 300 is anon-limiting embodiment of the subject matter of the current disclosure,and other embodiments, including different arrangements of symmetric andvertically asymmetric cells, are contemplated within the scope of thepresent disclosure. The elements portrayed in integrated circuit 300 aremerely demonstrative as to the relationships between cells in integratedcircuits, and not intended to exclude other configurations or layoutsthat also conform to the description provided herein. FIGS. 4-6 clarifysome arrangements cells in integrated circuit 300, including verticallysymmetric cells and/or vertically asymmetric (i.e., mirrored pairs) ofcells within integrated circuit 300. The arrangements shown in FIGS. 4-6clarify details of alignment of active areas of cells with differentcell lengths, and separation distances between active areas and barrierlines of the integrated circuit.

FIG. 4 is a plan view of a block 400 of cells in integrated circuit 300,according to some embodiments. The block of cells includes asymmetriccells 328 and 330, in column 302B, and symmetric cell 344, in column302C, as depicted in FIG. 3A, above. As described above, cells 328 and330 are vertically asymmetric cells. In vertically symmetric cells 328and 330, active areas are not evenly spaced between top and bottombarrier lines of the cells. Rather, cells 328 and 330 are a mirroredpair of cells sharing a mirrored cell boundary 316L. Active areas ofcells 328 and 330 are vertically offset within the cell areas to becloser to central barrier line 316 than to top barrier line 314 (forcell 328), or bottom barrier line 318 (for cell 330).

Cell 344 in column 302C is a symmetric cell having a cell length 402.Symmetric cell 344 has a top edge 344 t, a bottom edge 344 b, and a cellcenterline 344L along the second direction 103. Symmetric cell 344 hasan active area 345 with an active area centerline 345L that correspondsto cell centerline 344L. Active area 345 has an active area top edge 345t, and an active area bottom edge 345 b. Symmetric cell 344 has a topbarrier line 340 (with a top barrier line centerline 340L), a bottombarrier line 342 (with a bottom barrier centerline 342L). Cell 344 has afirst separation distance 404 between cell top edge 344 t (whichcorresponds with cell top barrier centerline 340L) and active area topedge 345 t, and the first separation distance 404 between cell bottomedge 344 b (which corresponds with cell bottom barrier centerline 342L)and active area bottom edge 345 b.

In column 302B, cell 328 has a top barrier line 314 (with a top barriercenterline 314L, which corresponds to top barrier centerline 340L ofsymmetric cell 344), a bottom barrier line corresponding to barrier line316 (with a barrier centerline 316L, which corresponds to active areacenterline 345L of symmetric cell 344), and a cell active area 329 withan active area top edge 329 t and an active area bottom edge 329 b.Barrier line 316 is a top barrier line for vertically asymmetric cell330. Barrier line 316 has a barrier centerline 316L that corresponds tocell top edge 330 t. Cell 330 has a bottom barrier line 318 (with abottom barrier centerline 318L, which corresponds to cell bottom barriercenterline 342L of cell 344). Cell 330 also has a cell active area 331with an active area top edge 331 t and an active area bottom edge 331 b.Vertically asymmetric cells 328 and 330 have a cell length 406, an outerseparation distance 405, and an inner separation distance 408. Celllength is measured from a cell top edge to a cell bottom edge. Celllength 406 is half the length of cell length 402 of symmetric cell 344.For cell 328, outer separation distance 405 corresponds to a distancebetween active area top edge 329 t and cell top edge 330 t. For cell330, outer separation distance 405 corresponds to a distance betweenactive area bottom edge 331 b and cell bottom edge 330 b. Innerseparation distance 408 corresponds to a distance between active areabottom edge 329 b and cell bottom edge 328 b (for cell 328), and to adistance between active area top edge 331 t and cell top edge 330 t (forcell 330). In vertically asymmetric cells, the inner separation distanceand the outer separation distance are different distances. In someembodiments, the inner separation distance is larger than the outerseparation distance. In some embodiments, the inner separation distanceis smaller than the outer separation distance.

Cells in cell libraries have different cell lengths according to thenumber of fins (poly lines converted into active devices or circuitelements) within active areas of the cells. “Short” cells have a lownumber of fins or poly lines in active areas, while “long” or largecells have large numbers of fins or poly lines in active areas thereof,as compared to the number of fins in a standard-length cell. Inpositioning short cells next to standard or long cells across columnboundaries (such as FIG. 4, column boundary 401) is that a centerline ofa long, or a standard, cell corresponds to a centerline of a sharedbarrier line between two short cells. When the length of the short cellis an even fraction of the standard cell length (½, ¼, and so forth), acenterline of the standard cell active area aligns with the centerlineof the shared barrier line, or the mirrored barrier line, between theshorter-cell length cells. (See, e.g., centerlines 316L and 344L in FIG.4.) Vertically asymmetric cells such as cells 328 and 330 of FIG. 4 havevertically offset active areas to align active area edges in thevertically asymmetric cells with an active area top edge or an activearea bottom edge in a symmetric cell in another column, is adjusted tomodify inner separation distance 308 enough to align active area topedge 329 t with active area top edge 345 t, and active area edge 332 bwith active area bottom edge 345 b. By aligning edges of active areas ineach column (e.g., between column 302B and 302C), the lines that make upactive areas in the vertically symmetric and the vertically asymmetriccells are not misaligned, and have improved device yield and deviceperformance.

FIG. 5 is a plan view of a block 500 of symmetric and verticallyasymmetric cells in integrated circuit 300, according to someembodiments. While FIG. 4 showed mirrored cell symmetry (also calledflipped cell symmetry) with a standard cell (cell 344) and two “short”cells (cells having a cell length less than the standard cell length402, FIG. 5 includes an arrangement of multiple standard cells (cells344, 346, and 350) in column 302C, next to two “long” cells (having acell length larger than the standard cell length), cells 356 and 360,while preserving alignment between topmost and bottommost active areaedges in topmost and bottommost cells of each column.

Cells 344, 346, and 350 are symmetric standard cells of integratedcircuit 300 located in column 302C. Top and bottom edges of active areasof each of cells 344, 346, and 350 are a first separation distance 520from a cell border (the centerline of the barrier line above or belowthe active area to which the separation distance is being measured).Thus, separation distance 520 exists between active area top edge 345 tand centerline 340L, active area top edge 347 t and centerline 342L,active area top edge 351 t and centerline 348L, and between active areabottom edge 345 b and centerline 342L, active area bottom edge 347 b andcenterline 348L, and active area bottom edge 351 b and centerline 352L.Cells 344, 346, and 350 have a cell length 502. Cell length is measuredbetween (for cell 344) cell top edge 344 t and cell bottom edge 344 b,(for cell 346) cell top edge 346 t and cell bottom edge 346 b, and (forcell 350) cell top edge 350 t and cell bottom edge 350 b). In someembodiments, cell length 502 is the standard cell length 402. Each ofcells 344, 346, and 350 have symmetric active areas between barrierlines of the cells.

Cells 356 and 360 have a cell length 504 that is greater than celllength 502. Cell length 504 is 1.5 times larger than cell length 502because cell 344 and cell 356 share a top barrier line (340/354) and atop border, and because cells 350 and 360 share a bottom barrier line(352 and 362) and a bottom border. Cells 356 and 360 share a boundaryline 358. Shared boundary line (or, mirrored boundary line) 358 is usedto measure an inner separation distance 506 between centerline 358L andactive area bottom edge 357 b (for cell 356), and centerline 358L andactive area top edge 361 t (for cell 360). An outer separation distancebetween barrier line 354 and active area top edge 357 t (for cell 356),and between barrier line 362 and active area bottom edge 361 b (for cell360) is different than inner separation distance 506. In someembodiments, the outer separation distance is larger than the innerseparation distance. In some embodiments, the outer separation distanceis smaller than the inner separation distance.

As described above with respect to FIG. 3B, active areas of cells thathave a cell length that is different than the standard cell length havea risk of some lines in the active areas thereof being trimmed, leadingto some narrow line segments at top or bottom ends of non-standardlength cells. Trimmed lines contribute to parasitic capacitance, powerconsumption, slower toggle times for a circuit element containing thecell, and/or device damage because trimmed lines are susceptible totipping and breakage in manufacturing. Trimmed lines also interfere withthe doping of non-trimmed lines in a cell, leading to a non-uniformdistribution of switching times and/or leakage current through a cell.By adjusting the size of an active area (e.g., in some embodiments, bymodifying a width of a barrier lines or isolation structures to consumethe trimmed portion during a barrier line formation step), the activeareas become vertically asymmetric and have uniform-width fins,producing fins with more uniform performance characteristics. Removingfins that are trimmed from an integrated circuit by modifying a barrierline width (to include an area that would have been occupied by atrimmed fin), manufacturing defects are reduced and product yieldincreased.

FIG. 6 is a plan view of a block of asymmetric cells in an integratedcircuit 300, according to some embodiments. Column 302A contains twocells: vertically asymmetric cells 304 and 306, as described above, withcell lengths 602 that are 1.5 times the standard cell length (see FIG.4, element 306). Column 302B contains six vertically asymmetric cells,cells 328, 330, 332, 334, 346, and 338, each having a cell length 603that is 0.5 times the standard cell length (see, e.g., FIG. 4, element308). Vertically asymmetric cells 304 and 306 comprise a block 602having a block length that is 3 times longer than the standard celllength, and cells 328, 330, 332, 334, 346, and 338 comprise three blocks604, 606, and 608, which, combined have a length that is 3 times thestandard cell length. Thus, centerlines 308L/314L for topmost barrierlines 308 and 314 correspond to top edges of cells 328 and 304, andcenterlines 312L/326L of bottommost barrier lines 312 and 326. Althoughnone of cells 304, 306, 328, and 338 are vertically symmetric cells, thecells have outer separation distances 610 that correspond to thestandard separation distance of a symmetric standard cell (see, e.g.,separation distance 304 of FIG. 3A, or separation distance 520 of FIG.5). Accordingly, outer separation distances of each of blocks 604, 606,and 608 are the same distance 610, equal to the standard separationdistance of a vertically symmetric cell in the integrated circuit 300.Further, inner separation distances of each or blocks 604, 606, and 608,of 302B, and of blocks 304 and 306 of column 302A, are the same distance610 around mirrored cell boundaries of the mirrored pairs of cells 304and 306 (line 310L), 320 and 330 (line 316L), 332 and 334 (line 320L),and 336 and 338 (line 324L). In some embodiments, inner separationdistance 610 is larger than outer separation distance 610. In someembodiments, inner separation distance 610 is smaller than outerseparation distance 610.

As described above with respect to FIG. 3B, active areas of cells thathave a cell length that is different than the standard cell length havea risk of some lines in the active areas thereof being trimmed, leadingto some narrow line segments at top or bottom ends of non-standardlength cells. Trimmed lines contribute to parasitic capacitance, powerconsumption, slower toggle times for a circuit element containing thecell, and/or device damage because trimmed lines are susceptible totipping and breakage in manufacturing. Trimmed lines also interfere withthe doping of non-trimmed lines in a cell, leading to a non-uniformdistribution of switching times and/or leakage current through a cell.By adjusting the size of an active area (e.g., in some embodiments, bymodifying a width of a barrier lines or isolation structures to consumethe trimmed portion during a barrier line formation step), the activeareas become vertically asymmetric and have uniform-width fins,producing fins with more uniform performance characteristics. Removingfins that are trimmed from an integrated circuit by modifying a barrierline width (to include an area that would have been occupied by atrimmed fin), manufacturing defects are reduced and product yieldincreased.

FIG. 7 is a cross-sectional view of a semiconductor device 700 accordingto some embodiments of the present disclosure. A description of device700 and the method 800 of making the device proceeds in parallel, below.FIG. 8 is a flow diagram of a method 800 of making an integrated circuithaving vertically asymmetric cells having mirrored symmetry across abarrier line. The method 800 includes an operation 810, wherein asubstrate layer 702 of an integrated circuit is formed. According tosome embodiments, the layer of substrate material includes, but is notlimited to: elementary semiconductor materials, compound semiconductormaterials, and/or alloy semiconductor materials. Examples of elementarysemiconductor materials include, but are not limited to, monocrystallinesilicon (Si), polycrystalline silicon (poly-Si), amorphous silicon(a-Si), germanium (Ge), and/or diamond (C). Examples of binary compoundsemiconductor materials include, but are not limited to, IV-IV materialsincluding silicon germanium (SiGe), germanium carbide (GeC), and siliconcarbide (SiC), and III-V materials including gallium arsenide (GaAs),gallium phosphide (GaP), indium phosphide (InP), indium arsenide (InAs),and/or indium antimonide (InSb). Examples of tertiary and quaternarycompound semiconductor materials include, but are not limited to, GaAsP,AlInAs, AlGaAs, GaInAs, GaInP, and/or GaInAsP.

In some embodiments, the semiconductor layer(s) incorporated in thesubstrate 702 are formed using a suitable technique or method including,but not limited to, metalorganic vapor phase epitaxy (MOVPE), molecularbeam epitaxy (MBE), hydride vapor phase epitaxy (HVPE), liquid phaseepitaxy (LPE), metal-organic molecular beam epitaxy (MOMBE), atomiclayer deposition (ALD), and/or combinations thereof.

In some embodiments, the substrate material includes both an insulatingmaterial and a semiconductor material to form asemiconductor-on-insulator (SOI) substrate. In some embodiments, SOIsubstrates include semiconductor layers formed on insulating material,such as silicon dioxide or sapphire. In some embodiments, the substrateincludes strained materials or epitaxially-grown layers that promotestrain within the substrate material to modify carrier mobility therein.Strain is induced into a semiconductor material in some embodiments byaddition of dopants to the substrate material.

Substrate materials are doped or undoped substrate materials, accordingto some embodiments, doped substrate materials include at least onep-type and/or n-type dopant depending on the functional and/orperformance target parameters for the semiconductor devices beingmanufactured on the substrate. The term “p-type” refers to the additionof impurities to an intrinsic semiconductor that creates deficiencies ofvalence electrons. Examples of p-type dopants, i.e., impurities,include, but are not limited to, boron, boron difluoride, gallium, andindium. “N-type” refers to the addition of impurities that contributesfree electrons to an intrinsic semiconductor. Examples of n-typedopants, i.e., impurities, include, but are not limited to, antimony,arsenic, and phosphorous. In some embodiments, the semiconductorsubstrate 702 is doped with p-type dopants such as boron or borondifluoride.

The method 800 also includes an operation 820, wherein a pattern istransferred to a top surface of the substrate layer. In someembodiments, the pattern is transferred to a layer of photoresist. Insome embodiments, the pattern is transferred to a hard or soft masklayer after an etch process using a layer of photoresist, the hard orsoft mask layer being suitable for transferring the pattern to thesubstrate material. Mask layers include, according to embodiments,photoresist layers, hard mask layers soft mask layers, hybrid hard/softmask layers (bilayers) with individual films suited to resisting etchchemistry of a subsequently applied etching process for a substratematerial. The pattern includes, in some embodiments, a patterncorresponding to fins 706 of the semiconductor substrate 702.

A type of mask material, and mask layer thickness is regulated by, thechemical composition of the substrate material to which the pattern istransferred during a subsequent etch process. Suitable mask materialsinclude, but are not limited to, polyimide, silicon oxide, siliconnitride, silicon oxynitride, silicon oxycarbide, or combinationsthereof, as well as combinations of organic or mixed (organic/inorganic)photosensitive materials or materials sensitive to electron beam epitaxyor other pattern transfer methods.

Mask materials are deposited, according to embodiments of the method, byvapor deposition, including chemical vapor deposition (CVD), physicalvapor deposition (PVD), plasma enhanced chemical vapor deposition(PECVD), epitaxial growth, sputtering or other suitable depositionmethods.

Pattern transfer to a mask layer is accomplished, by photolithography,electron beam patterning techniques, or other pattern transfer methodsknown to persons of skill in the art. Photolithographic methods ofpattern transfer include operations of depositing (by, e.g., spincoating) photoresist material onto a substrate material, baking (todrive out solvent) the photoresist material, aligning the substrate withan illuminated patterning element of a photolithography tool, exposingthe photoresist layer to illumination from the lithography tool,developing the exposed photoresist film to expose a first portion of thesubstrate material, and cleaning the photoresist material to removedefects prior to pattern transfer from the photoresist into a furthermask (e.g., a hard mask or soft mask) or into the substrate. Patterningtemplates for transferring the pattern to photoresist material includephotolithography reticles that selectively interact with illuminationfrom the photolithography or electron beam tool to create patterns ofconstructive and destructive interference, and to block or allow passageof light/electrons, onto the photoresist or other photosensitivematerial to receive a pattern predicated on a mask or reticle pattern ofthe patterning template.

The method 800 further includes operation 830, wherein the pattern isetched into the substrate material. Etching is, according to someembodiments, a dry etch or plasma etch process wherein gaseous or plasmaspecies are directed onto exposed portions of the substrate to reactwith the substrate material where the mask material is absent. Etchingis, according to some embodiments, a wet etching process where a waferis immersed into, or coated by, a solution with reactive agents thatremoved exposed portions of the substrate. In plasm etching, mask layersare etched using plasmas generated from gas mixtures comprising at leastone halogen-containing gas, and may include one or more of CF₄, SF₆,NF₃, Cl₂, CCl₂F₂, SiCl₄, BCl₂, or a combination thereof. Wet etchingincludes, according to the substrate material being etched, liquidsolutions that contain reactant species that consume exposed substratematerial where the mask layer is absent. Wet etching processes sometimesinclude water. According to some embodiments, wet etching processes arefree of water in the reactant solution applied to a wafer surface toetch the partially-substrate material. Wet etching processes include oneor more of citric acid (C₆H₈O₇), hydrogen peroxide (H₂O₂), nitric acid(HNO₃), sulfuric acid (H₂SO₄), hydrochloric acid (HCl), acetic acid(CH₃CO₂H), hydrofluoric acid (HF), buffered hydrofluoric acid (BHF),phosphoric acid (H₃PO₄), ammonium fluoride (NH₄F) potassium hydroxide(KOH), ethylenediamine pyrocatechol (EDP), tetramethylammonium hydroxide(TMAH), or a combination thereof, applied to a surface by immersing thesubstrate (on a semiconductor wafer) into a tank, or by spraying theetchant solution onto a surface. Wet etching processes include,according to some embodiments, neutralizing steps and/or rinsing stepsto halt chemical reactions on a wafer surface and/or remove reactantspecies from the wafer surface to halt substrate removal.

Fins 706, after etching, have a composition matching the composition ofthe substrate material prior to etching. During some operations,insulating material 707 is deposited into spaces 708 between fins 706.In some operations, the insulating material 707 is recessed so that alower portion 706A is masked by the insulating material 707, while anupper portion 706B is non masked by the insulating material. The exposedupper portion 706B undergoes doping or implantation in order to modifythe electrical characteristics of the exposed portion of semiconductormaterial in order to adjust electrical characteristics of the cell.Subsequent to doping or implanting the exposed upper portion 706B, adeep isolation structure 710 is formed next to the fins 706. A deepopening is formed in the substrate, having a depth in the substrate 702that is greater than the depth of the space 708 between the fins 706.The deep opening is then filled with an insulating material toelectrically isolate the fins from fins in adjacent cells of theintegrated circuit. Subsequent to depositing the insulating material fordeep isolation structure 710, the insulating material is recessed, asdescribed above with a wet or plasma etch, and a gate electrode 712 isformed across the exposed upper portion 706B of fins 706.

Other manufacturing processes for integrated circuits having a singlesize of analog cells, simplification of layout and manufacturing may beachieved by using symmetric spacing of the elements of the analog cell.Symmetric layout of analog cell elements indicate that each cell lengthand each cell length are the same between adjoining/abutting cells, andthat the active areas of each analog cell are aligned with co-linearedges in a first direction (across barrier lines at active area borders)and a second direction (parallel to the barrier lines) that separateanalog cell active areas. Analog cell symmetric layout includes asimilar separation between one side of the analog cell active area, andthe nearest barrier line or isolation structure to that analog cellactive area. Such symmetric analog cell layout simplifies manufacturingbecause photolithographic masking is simplified, and because a mandrel,used to produce sub-lithographic resolution features, may be generatedwith less line width variation across the array of analog cells in theintegrated circuit. Abutting analog cells (i.e., cells that adjoin eachother without an intervening barrier line or isolation structure,automatically align both barrier line and active area cell features.However, reliance on only a single size of analog cell may berestrictive in terms of integrated circuit design.

FIG. 9 is a block diagram of an electronic design automation (EDA)system 900, in accordance with some embodiments. Methods describedherein of generating cell layout diagrams, in accordance with one ormore embodiments, are implementable, for example, using EDA system 900,in accordance with some embodiments. In some embodiments, EDA system 900is a general purpose computing device including a hardware processor 902and a non-transitory, computer-readable storage medium 904. Storagemedium 904, amongst other things, is encoded with, i.e., stores,computer program code 906, i.e., a set of executable instructions.Execution of instructions 906 by hardware processor 902 represents (atleast in part) an EDA tool which implements a portion or all of, e.g.,the methods described herein in accordance with one or more(hereinafter, the noted processes and/or methods).

Processor 902 is electrically coupled to computer-readable storagemedium 904 via a bus 908. Processor 902 is also electrically coupled toan I/O interface 910 by bus 908. A network interface 912 is alsoelectrically connected to processor 902 via bus 908. Network interface912 is connected to a network 914, so that processor 902 andcomputer-readable storage medium 904 are capable of connecting toexternal elements via network 914. Processor 902 is configured toexecute computer program code 906 encoded in computer-readable storagemedium 904 in order to cause system 900 to be usable for performing aportion or all of the noted processes and/or methods. In one or moreembodiments, processor 902 is a central processing unit (CPU), amulti-processor, a distributed processing system, an applicationspecific integrated circuit (ASIC), and/or a suitable processing unit.

In one or more embodiments, computer-readable storage medium 904 is anelectronic, magnetic, optical, electromagnetic, infrared, and/or asemiconductor system (or apparatus or device). For example,computer-readable storage medium 904 includes a semiconductor orsolid-state memory, a magnetic tape, a removable computer diskette, arandom access memory (RAM), a read-only memory (ROM), a rigid magneticdisk, and/or an optical disk. In one or more embodiments using opticaldisks, computer-readable storage medium 904 includes a compact disk-readonly memory (CD-ROM), a compact disk-read/write (CD-R/W), and/or adigital video disc (DVD).

In one or more embodiments, storage medium 904 stores computer programcode 906 configured to cause system 900 (where such execution represents(at least in part) the EDA tool) to be usable for performing a portionor all of the noted processes and/or methods. In one or moreembodiments, storage medium 904 also stores information whichfacilitates performing a portion or all of the noted processes and/ormethods. In one or more embodiments, storage medium 904 stores library907 of standard cells including such standard cells as disclosed herein.

EDA system 900 includes I/O interface 910. I/O interface 910 is coupledto external circuitry. In one or more embodiments, I/O interface 910includes a keyboard, keypad, mouse, trackball, trackpad, touchscreen,and/or cursor direction keys for communicating information and commandsto processor 902.

EDA system 900 also includes network interface 912 coupled to processor902. Network interface 912 allows system 900 to communicate with network914, to which one or more other computer systems are connected. Networkinterface 912 includes wireless network interfaces such as BLUETOOTH,WIFI, WIMAX, GPRS, or WCDMA; or wired network interfaces such asETHERNET, USB, or IEEE-1364. In one or more embodiments, a portion orall of noted processes and/or methods, is implemented in two or moresystems 900.

System 900 is configured to receive information through I/O interface910. The information received through I/O interface 910 includes one ormore of instructions, data, design rules, libraries of standard cells,and/or other parameters for processing by processor 902. The informationis transferred to processor 902 via bus 908. EDA system 900 isconfigured to receive information related to a UI through I/O interface910. The information is stored in computer-readable medium 904 as userinterface (UI) 942.

In some embodiments, a portion or all of the noted processes and/ormethods is implemented as a standalone software application forexecution by a processor. In some embodiments, a portion or all of thenoted processes and/or methods is implemented as a software applicationthat is a part of an additional software application. In someembodiments, a portion or all of the noted processes and/or methods isimplemented as a plug-in to a software application. In some embodiments,at least one of the noted processes and/or methods is implemented as asoftware application that is a portion of an EDA tool. In someembodiments, a portion or all of the noted processes and/or methods isimplemented as a software application that is used by EDA system 900. Insome embodiments, a layout diagram which includes standard cells isgenerated using a tool such as VIRTUOSO® available from CADENCE DESIGNSYSTEMS, Inc., or another suitable layout generating tool.

In some embodiments, the processes are realized as functions of aprogram stored in a non-transitory computer readable recording medium.Examples of a non-transitory computer readable recording medium include,but are not limited to, external/removable and/or internal/built-instorage or memory unit, e.g., one or more of an optical disk, such as aDVD, a magnetic disk, such as a hard disk, a semiconductor memory, suchas a ROM, a RAM, a memory card, and the like.

FIG. 10 is a block diagram of an integrated circuit (IC) manufacturingsystem 1000, and an IC manufacturing flow associated therewith, inaccordance with some embodiments. In some embodiments, based on a layoutdiagram, at least one of (A) one or more semiconductor masks or (B) atleast one component in a layer of a semiconductor integrated circuit isfabricated using manufacturing system 1000.

In FIG. 10, IC manufacturing system 1000 includes entities, such as adesign house 1020, a mask house 1030, and an IC manufacturer/fabricator(“fab”) 1050, that interact with one another in the design, development,and manufacturing cycles and/or services related to manufacturing an ICdevice 1060. The entities in system 1000 are connected by acommunications network. In some embodiments, the communications networkis a single network. In some embodiments, the communications network isa variety of different networks, such as an intranet and the Internet.The communications network includes wired and/or wireless communicationchannels. Each entity interacts with one or more of the other entitiesand provides services to and/or receives services from one or more ofthe other entities. In some embodiments, two or more of design house1020, mask house 1030, and IC fab 1050 is owned by a single largercompany. In some embodiments, two or more of design house 1020, maskhouse 1030, and IC fab 1050 coexist in a common facility and use commonresources.

Design house (or design team) 1020 generates an IC design layout diagram1022. IC design layout diagram 1022 includes various geometricalpatterns designed for an IC device 1060. The geometrical patternscorrespond to patterns of metal, oxide, or semiconductor layers thatmake up the various components of IC device 1060 to be fabricated. Thevarious layers combine to form various IC features. For example, aportion of IC design layout diagram 1022 includes various IC features,such as an active region, gate electrode, source and drain, metal linesor vias of an interlayer interconnection, and openings for bonding pads,to be formed in a semiconductor substrate (such as a silicon wafer) andvarious material layers disposed on the semiconductor substrate. Designhouse 1020 implements a proper design procedure to form IC design layoutdiagram 1022. The design procedure includes one or more of logic design,physical design or place and route. IC design layout diagram 1022 ispresented in one or more data files having information of thegeometrical patterns. For example, IC design layout diagram 1022 can beexpressed in a GDSII file format or DFII file format.

Mask house 1030 includes data preparation 1032 and mask fabrication1044. Mask house 1030 uses IC design layout diagram 1022 to manufactureone or more masks 1045 to be used for fabricating the various layers ofIC device 1060 according to IC design layout diagram 1022. Mask house1030 performs mask data preparation 1032, where IC design layout diagram1022 is translated into a representative data file (“RDF”). Mask datapreparation 1032 provides the RDF to mask fabrication 1044. Maskfabrication 1044 includes a mask writer. A mask writer converts the RDFto an image on a substrate, such as a mask (reticle) 1045 or asemiconductor wafer 1053. The design layout diagram 1022 is manipulatedby mask data preparation 1032 to comply with particular characteristicsof the mask writer and/or requirements of IC fab 1050. In FIG. 10, maskdata preparation 1032 and mask fabrication 1044 are illustrated asseparate elements. In some embodiments, mask data preparation 1032 andmask fabrication 1044 can be collectively referred to as mask datapreparation.

In some embodiments, mask data preparation 1032 includes opticalproximity correction (OPC) which uses lithography enhancement techniquesto compensate for image errors, such as those that can arise fromdiffraction, interference, other process effects and the like. OPCadjusts IC design layout diagram 1022. In some embodiments, mask datapreparation 1032 includes further resolution enhancement techniques(RET), such as off-axis illumination, sub-resolution assist features,phase-shifting masks, other suitable techniques, and the like orcombinations thereof. In some embodiments, inverse lithographytechnology (ILT) is also used, which treats OPC as an inverse imagingproblem.

In some embodiments, mask data preparation 1032 includes a mask rulechecker (MRC) that checks the IC design layout diagram 1022 that hasundergone processes in OPC with a set of mask creation rules whichcontain certain geometric and/or connectivity restrictions to ensuresufficient margins, to account for variability in semiconductormanufacturing processes, and the like. In some embodiments, the MRCmodifies the IC design layout diagram 1022 to compensate for limitationsduring mask fabrication 1044, which may undo part of the modificationsperformed by OPC in order to meet mask creation rules.

In some embodiments, mask data preparation 1032 includes lithographyprocess checking (LPC) that simulates processing that will beimplemented by IC fab 1050 to fabricate IC device 1060. LPC simulatesthis processing based on IC design layout diagram 1022 to create asimulated manufactured device, such as IC device 1060. The processingparameters in LPC simulation can include parameters associated withvarious processes of the IC manufacturing cycle, parameters associatedwith tools used for manufacturing the IC, and/or other aspects of themanufacturing process. LPC takes into account various factors, such asaerial image contrast, depth of focus (“DOF”), mask error enhancementfactor (“MEEF”), other suitable factors, and the like or combinationsthereof. In some embodiments, after a simulated manufactured device hasbeen created by LPC, if the simulated device is not close enough inshape to satisfy design rules, OPC and/or MRC are be repeated to furtherrefine IC design layout diagram 1022.

It should be understood that the above description of mask datapreparation 1032 has been simplified for the purposes of clarity. Insome embodiments, data preparation 1032 includes additional featuressuch as a logic operation (LOP) to modify the IC design layout diagram1022 according to manufacturing rules. Additionally, the processesapplied to IC design layout diagram 1022 during data preparation 1032may be executed in a variety of different orders.

After mask data preparation 1032 and during mask fabrication 1044, amask 1045 or a group of masks 1045 are fabricated based on the modifiedIC design layout diagram 1022. In some embodiments, mask fabrication1044 includes performing one or more lithographic exposures based on ICdesign layout diagram 1022. In some embodiments, an electron-beam(e-beam) or a mechanism of multiple e-beams is used to form a pattern ona mask (e.g., a photomask, or a reticle) 1045 based on the modified ICdesign layout diagram 1022. Mask 1045 can be formed in varioustechnologies. In some embodiments, mask 1045 is formed using binarytechnology. In some embodiments, a mask pattern includes opaque regionsand transparent regions. A radiation beam, such as an ultraviolet (UV)beam, used to expose the image sensitive material layer (e.g.,photoresist) which has been coated on a wafer, is blocked by the opaqueregion and transmits through the transparent regions. In one example, abinary mask version of mask 1045 includes a transparent substrate (e.g.,fused quartz) and an opaque material (e.g., chromium) coated in theopaque regions of the binary mask. In another example, mask 1045 isformed using a phase shift technology. In a phase shift mask (PSM)version of mask 1045, various features in the pattern formed on thephase shift mask are configured to have proper phase difference toenhance the resolution and imaging quality. In various examples, thephase shift mask can be attenuated PSM or alternating PSM. The mask(s)generated by mask fabrication 1044 is used in a variety of processes.For example, such a mask(s) is used in an ion implantation process toform various doped regions in semiconductor wafer 1053, in an etchingprocess to form various etching regions in semiconductor wafer 1053,and/or in other suitable processes.

IC fab 1050 includes wafer fabrication 1052. IC fab 1050 is an ICfabrication business that includes one or more manufacturing facilitiesfor the fabrication of a variety of different IC products. In someembodiments, IC Fab 1050 is a semiconductor foundry. For example, theremay be a manufacturing facility for the front end fabrication of aplurality of IC products (front-end-of-line (FEOL) fabrication), while asecond manufacturing facility may provide the back end fabrication forthe interconnection and packaging of the IC products (back-end-of-line(BEOL) fabrication), and a third manufacturing facility may provideother services for the foundry business.

IC fab 1050 uses mask(s) 1045 fabricated by mask house 1030 to fabricateIC device 1060. Thus, IC fab 1050 at least indirectly uses IC designlayout diagram 1022 to fabricate IC device 1060. In some embodiments,semiconductor wafer 1053 is fabricated by IC fab 1050 using mask(s) 1045to form IC device 1060. In some embodiments, the IC fabrication includesperforming one or more lithographic exposures based at least indirectlyon IC design layout diagram 1022. Semiconductor wafer 1053 includes asilicon substrate or other proper substrate having material layersformed thereon. Semiconductor wafer 1053 further includes one or more ofvarious doped regions, dielectric features, multilevel interconnects,and the like (formed at subsequent manufacturing steps).

Details regarding an integrated circuit (IC) manufacturing system (e.g.,system 1000 of FIG. 10), and an IC manufacturing flow associatedtherewith are found, e.g., in U.S. Pat. No. 9,256,709, granted Feb. 9,2016, U.S. Pre-Grant Publication No. 20150278429, published Oct. 1,2015, U.S. Pre-Grant Publication No. 20140040838, published Feb. 6,2014, and U.S. Pat. No. 7,260,442, granted Aug. 21, 2007, the entiretiesof each of which are hereby incorporated by reference.

In some integrated circuits, analog cells have different cell lengthsbetween barrier lines of the analog cell. Cell length of a standard cellis also referred to as a standard length. A cell length of anon-standard cell may be a fraction of the standard length (e.g., 0.5,0.3, . . . ) or may be a non-integer multiple (e.g., 1.5, 2.5, . . . )of the standard length. In an integrated circuit having a plurality ofanalog cells, some of which have a standard cell size, and some of whichhave a different cell length (either a fractional length, or anon-integer multiple length), barrier lines or isolation structures oftwo adjoining cells (in the second direction) sometimes align, but theactive areas bordered by the barrier lines/isolation structures havedifferent lengths in the first direction. When the cell lengths of thecells, in the first direction, is the result of a number of fins in theadjoining cells, a high-fin area (e.g., an active area with a largernumber of fins) aligns, at one edge, with a lower-fin area (e.g., a“standard cell” or a “normal cell”). In some embodiments of integratedcircuits, a number of high-fin active areas in one column adjoins adifferent number of standard cell active areas in an adjoining column,and the overall length of the first number of high-fin active areas, orcells, is the same as the second number of standard cells, in theadjoining column. The top-most and bottom-most barrier lines of thecells in each column align, while the intermediate barrier lines, orisolation structures, in each column only sometimes align with a barrierline or isolation in the adjoining column. A symmetric layout occurswhen the number and size of each active area (or portion of the activearea) in the adjoining columns is symmetric with respect to a centerlinelocated midway between the top and bottom barrier lines of the activeareas of the two columns. The centerline between the top and bottombarrier lines is called a mirror line.

Deliberate vertical asymmetry, within a single cell of an integratedcircuit, of the active area of the cell, between top and bottom edges ofthe cell, in order to align an edge or border of the active area with anedge or border of an active area in a different column of the integratedcircuit, promotes higher yields of integrated circuit manufacturingprocess and reduces dimensional variation among cell elements in theintegrated circuit. Vertically asymmetric cells are arranged in pairswith mirroring symmetry (also called flipped symmetry) across a sharedor mirrored cell boundary to promote reduced-defect manufacturingprocesses and to simplify layout of integrated circuits having cellswith vertical asymmetry.

Some aspects of the present disclosure relate to an integrated circuit,comprising: a first cell in a first column of cells, the first cellhaving a first length in a first direction, a first barrier line at afirst cell top end, a second barrier line at a first cell bottom end, afirst cell active area between the first barrier line and the secondbarrier line, a first separation distance between a top edge of thefirst cell active area and the first barrier line, and a secondseparation distance between the bottom edge of the first cell activearea and the second barrier line; a second cell in the first column ofcells, the second cell having the first length in a first direction, athird barrier line at a second cell top end, a fourth barrier line at asecond cell bottom end, and a second cell active area between the thirdbarrier line and the fourth barrier line, the second separation distancebetween a top edge of the second cell active area and the third barrierline, and the first separation distance between a bottom edge of thesecond cell active area and the fourth barrier line; a third cell in asecond direction from the first column of cells, the second directionbeing different from the first direction, the third cell being in asecond column and having a second length in the first direction, thesecond length being different from the first length, a fifth barrierline at a third cell top end, a sixth barrier line at a third cellbottom end, and a third cell active area between the fifth barrier lineand the sixth barrier line, the first separation distance between a topedge of the third cell active area and the fifth barrier line, and athird separation distance between a bottom edge of the third cell activearea and the sixth barrier line, wherein the first separation distanceand the third separation distance are different from the secondseparation distance. In some embodiments, the first separation distanceequals the third separation distance. In some embodiments, the secondseparation distance is larger than the first separation distance. Insome embodiments, the second separation distance is smaller than thefirst separation distance. In some embodiments, the third separationdistance is smaller than the second separation distance. In someembodiments, the second cell length is twice the first cell length. Insome embodiments, the first cell length is 1.5 times the second celllength. In some embodiments, the first separation distance, the secondseparation distance, and the third separation distance are differentdistances. In some embodiments, the circuit further comprises a fourthcell in the second column, the fourth cell having the second length inthe first direction, a seventh barrier line at a fourth cell top end, aneighth barrier line at a fourth cell bottom end, and a fourth cellactive area between the seventh barrier line and the eighth barrierline, the third separation distance between a top edge of the fourthcell active area and the seventh barrier line, and the first separationdistance between a bottom edge of the fourth cell active area and theeighth barrier line, wherein the first separation distance and the thirdseparation distance are different form the second separation distance.In some embodiments, the first barrier line aligns with the fifthbarrier line along the second direction, and the fourth barrier linealigns with the eighth barrier line along the second direction.

Some aspects of the present disclosure relate to a method of making anintegrated circuit, comprising: depositing a layer of material onto asubstrate, transferring a first pattern from the first patterningtemplate to a top surface of the layer of material; and etching thefirst pattern into the layer of material, wherein the first patterncomprises barrier lines of a first a first cell and a second cell in afirst column, and a third cell and a fourth cell in a second column,wherein a first cell active area top edge aligns, in a first direction,with a third cell active area top edge, and a second cell active areabottom edge aligns, along in the first direction, with a fourth cellactive area top edge, and wherein the third and fourth cells arevertically asymmetric cells with regard to the first direction. In someembodiments, the method further comprises transferring a second patternfrom a second patterning template to the top surface of the layer ofmaterial, wherein the second pattern corresponds to an array of fins fortransistors of the integrated circuit. In some embodiments, the methodfurther comprises filling spaces between fins with a dielectricmaterial. In some embodiments, the method further comprises depositingan insulating material into the barrier lines of the first cell, thesecond cell, the third cell, and the fourth cell of the integratedcircuit. In some embodiments, the method further comprises depositing atleast one dopant into fins of the array of fins. In some embodiments,depositing at least one dopant further comprises implanting dopants intoa top portion of fins to form channel regions of the fins. In someembodiments, the method further comprises adjusting a width of a barrierline between two adjoining cells to eliminate a trimmed line from anactive area of a cell the integrated circuit.

Some aspects of the present disclosure relate to an integrated circuithaving a first cell having a first cell length in a first direction, thefirst cell having a first cell active area with a first number of finsbetween a first barrier line and a second barrier line, the firstbarrier line being a first distance from the first cell active area, andthe second barrier line being a second distance from the first cellactive area, the first and second distances being different distances;and a second cell having a second cell length in the first direction,the second cell having a second cell active area with a second number offins between a third barrier line and a fourth barrier line, the thirdbarrier line and the fourth barrier line being different distances fromthe second cell active area, wherein the second cell length is ⅓ thefirst cell length. In some embodiments, the circuit further comprises athird cell having the first cell length, a third cell active area havingthe first number of fins between a fifth barrier line and the secondbarrier line, the fifth barrier line being the first distance from thethird cell active area, and the second barrier line being the seconddistance from the third cell active area.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. An integrated circuit, comprising: a first cellin a first column, the first cell having a first length in a firstdirection, a first barrier line at a first cell top end, a secondbarrier line at a first cell bottom end, a first cell active areabetween the first barrier line and the second barrier line, a firstseparation distance between a top edge of the first cell active area andthe first barrier line, and a second separation distance between abottom edge of the first cell active area and the second barrier line; asecond cell in the first column, the second cell having the first lengthin the first direction, a third barrier line at a second cell top end, afourth barrier line at a second cell bottom end, and a second cellactive area between the third barrier line and the fourth barrier line,the second separation distance between a top edge of the second cellactive area and the third barrier line, and the first separationdistance between a bottom edge of the second cell active area and thefourth barrier line; a third cell in a second column, different from thefirst column, wherein the third cell has a second length in the firstdirection, the second length being different from the first length, afifth barrier line at a third cell top end, a sixth barrier line at athird cell bottom end, and a third cell active area between the fifthbarrier line and the sixth barrier line, the first separation distancebetween a top edge of the third cell active area and the fifth barrierline, and a third separation distance between a bottom edge of the thirdcell active area and the sixth barrier line, wherein the firstseparation distance and the third separation distance are different fromthe second separation distance, the first barrier line aligns, in thefirst direction, with the fifth barrier line, and the fourth barrierline aligns, in the first direction, with the sixth barrier line.
 2. Thecircuit of claim 1, wherein the first separation distance equals thethird separation distance.
 3. The circuit of claim 1, wherein the secondseparation distance is larger than the first separation distance.
 4. Thecircuit of claim 1, wherein the second separation distance is smallerthan the first separation distance.
 5. The circuit of claim 1, whereinthe third separation distance is larger than the first separationdistance.
 6. The circuit of claim 1, wherein the third separationdistance is smaller than the second separation distance.
 7. The circuitof claim 1, wherein the second cell length is twice the first celllength.
 8. The circuit of claim 1, wherein the first cell length is 1.5times the second cell length.
 9. The circuit of claim 1, wherein thefirst separation distance, the second separation distance, and the thirdseparation distance are different distances.
 10. The circuit of claim 1,further comprising a fourth cell in the second column, the fourth cellhaving the second length in the first direction, a seventh barrier lineat a fourth cell top end, an eighth barrier line at a fourth cell bottomend, and a fourth cell active area between the seventh barrier line andthe eighth barrier line, the third separation distance between a topedge of the fourth cell active area and the seventh barrier line, andthe first separation distance between a bottom edge of the fourth cellactive area and the eighth barrier line, wherein the first separationdistance and the third separation distance are different form the secondseparation distance.
 11. The circuit of claim 10, wherein the firstbarrier line aligns with the fifth barrier line along the seconddirection, and the fourth barrier line aligns with the eighth barrierline along the second direction.
 12. A method of making an integratedcircuit, comprising: depositing a layer of material onto a substrate;transferring a first pattern from a first patterning template to a topsurface of the layer of material; and etching the first pattern into thelayer of material, wherein the first pattern comprises barrier lines ofa first cell and a second cell in a first column, and a third cell and afourth cell in a second column, wherein a first cell active area topedge aligns, in a first direction, with a third cell active area topedge, and a second cell active area bottom edge aligns, in the firstdirection, with a fourth cell active area top edge, and wherein thethird and fourth cells are vertically asymmetric cells with regard tothe first direction.
 13. The method of claim 12, further comprisingtransferring a second pattern from a second patterning template to thetop surface of the layer of material, wherein the second patterncorresponds to an array of fins for transistors of the integratedcircuit.
 14. The method of claim 12, further comprising filling spacesbetween fins with a dielectric material.
 15. The method of claim 11,further comprising depositing an insulating material into the barrierlines of the first cell, the second cell, the third cell, and the fourthcell of the integrated circuit.
 16. The method of claim 12, furthercomprising depositing at least one dopant into fins of the array offins.
 17. The method of claim 16, wherein the depositing at least onedopant further comprises implanting dopants into a top portion of finsto form channel regions of the fins.
 18. The method of claim 11, furthercomprising adjusting a width of a barrier line between two adjoiningcells to eliminate a trimmed line from an active area of a cell in theintegrated circuit.
 19. An integrated circuit, comprising: a first cellhaving a first cell length in a first direction, the first cell having afirst cell active area with a first number of fins between a firstbarrier line and a second barrier line, the first barrier line being afirst distance from the first cell active area, and the secondbarrierline being a second distance from the first cell active area, thefirst and second distances being different distances; and a second cellhaving a second cell length in the first direction, the second cellhaving a second cell active area with a second number of fins between athird barrierline and a fourth barrierline, the third barrierline andthe fourth barrierline being different distances from the second cellactive area, the third barrier line being aligned in the first directionwith the first barrier line, wherein the second cell length is 3 timesthe first cell length.
 20. The circuit of claim 19, further comprising athird cell having the first cell length, a third cell active area havingthe first number of fins between a fifth barrier line and the secondbarrier line, the fifth barrier line being the first distance from thethird cell active area, and the second barrier line being the seconddistance from the third cell active area.